Compound semiconductor solar cells including semiconductor layers, e.g., III-V compound semiconductor layers, are conventionally used as power sources in the outer space for their having high photoelectric conversion efficiency. The compound semiconductor solar cells to be used in the outer space are required to have high photoelectric conversion efficiency and light weight, as well as to be capable of being manufactured at low cost, in order to reduce costs such as expense for rocket launches.
For reducing the weight of a compound semiconductor solar cell that is fabricated by epitaxially growing a semiconductor layer, such as a III-V compound semiconductor layer, on a semiconductor substrate, a method has been proposed by which etching is performed on the semiconductor layer to separate the semiconductor layer from the semiconductor substrate, thereby achieving weight reduction. According to this method, repetitive application of the separated semiconductor substrate to the epitaxial growing process allows for cost-cut for the compound semiconductor solar cells as well.
For example, Japanese Patent Laying-Open No. 2004-319934 (Patent Document 1) discloses a method wherein a semiconductor layer is epitaxially grown on a semiconductor substrate with an etching layer interposed therebetween, and then tensile stress is applied to the semiconductor layer with an etching mask and a supporting substrate bonded to the semiconductor layer, so as to separate the semiconductor layer from the semiconductor substrate.
In addition, Japanese Patent Laying-Open No. 07-226528 (Patent Document 2) discloses a method wherein a silicon semiconductor layer formed on a substrate is etched through through holes, so as to separate the substrate from the semiconductor layer.    Patent Document 1: Japanese Patent Laying-Open No. 2004-319934    Patent Document 2: Japanese Patent Laying-Open No. 07-226528